The present invention relates to the removal of dissolved oxygen from fuels, and more particularly to electrochemically converting the oxygen to water.
The presence of dissolved oxygen in hydrocarbon jet fuels may be objectionable because it supports oxidation reactions that yield undesirable by-products. Jet fuel is often utilized in aircraft as a coolant for various systems in the aircraft. Dissolution of air in jet fuel results in an approximately 70 ppm oxygen concentration. When aerated fuel is heated between 350° F. and 850° F. the oxygen initiates free radical reactions of the fuel resulting in deposits commonly referred to as “coke” or “coking.” Coke may be detrimental to the fuel lines and may inhibit combustion. The formation of such deposits may impair the normal functioning of a fuel delivery system, either with respect to an intended heat exchange function or the efficient injection of fuel.
Typically, lowering the oxygen concentration to 2 ppm is sufficient to overcome the coking problem. Various conventional fuel deoxygenation techniques are currently utilized.
One conventional Fuel Stabilization Unit (FSU) utilized in the aircraft field removes oxygen from jet fuel by inducing an oxygen pressure gradient across a membrane permeable to oxygen. Although quite effective, the gradient is produced by vacuum on one side of the membrane. As the vacuum also introduces mechanical forces on the membrane, the membrane is supported on a porous stainless steel plate, which is relatively expensive and may be a diffusion barrier requiring a relative increase in the unit size. Mechanical pumps and vacuum housings are also required which further increases the size and weight of the system.
Accordingly, it is desirable to provide a method and system for the deoxygenation of hydrocarbon fuel which minimizes coking in an inexpensive, size and weight efficient system.